The 4-6 year booster — tetanus, diphtheria, pertussis, and polio (Adacel®-Polio or Boostrix®-Polio)
A booster given before school starts, reinforcing protection from the infant series.
The Tdap-IPV booster reinforces protection against four diseases your child first received protection from as a baby.
| Disease | What parents might notice | How it spreads | Why it can be serious | How vaccination helps |
|---|---|---|---|---|
| Tetanus | Muscle stiffness and spasms, often starting in the jaw ("lockjaw"). | Bacteria entering the body through a cut or wound — it does not spread from person to person. | Severe muscle spasms can affect breathing and be life-threatening. | The booster keeps protection topped up, which is important as children become more active and prone to cuts and scrapes. |
| Diphtheria | Sore throat, fever, and a thick coating at the back of the throat that can make breathing difficult. | Coughing, sneezing, and close contact. | Can cause breathing problems, heart failure, and other serious complications. | The booster reinforces the immune system's ability to neutralize the diphtheria toxin. |
| Pertussis (whooping cough) | Severe coughing fits, sometimes with a "whooping" sound when breathing in. | Coughing and sneezing. | Protection from the infant doses fades over time, so a booster helps maintain it through the school years — and reduces spread to vulnerable infants. | The booster refreshes protection as the earlier doses begin to wane. |
| Polio | Often no symptoms; in some cases, flu-like illness or, rarely, paralysis. | Contact with an infected person's stool, or sometimes respiratory droplets. | Can cause permanent paralysis in a small number of cases. | The booster maintains protection against polio as part of the pre-school top-up. |
Why at 4–6 years? Protection from the infant series (given at 2, 4, 6, and 18 months) gradually fades over the early years. A booster around the time a child starts school refreshes that protection for the school years ahead — which is also why it lines up with school entry.
Why only one dose now? Because the immune system was already "primed" by the infant series, a single booster dose is enough to lift protection back up at this age. It's not a fresh start — it builds on what's already there.
What if it's late? If the booster is delayed, it can generally still be given — being late doesn't mean restarting the whole series. A healthcare provider or public health unit can confirm timing. See the Catch-Up & Missing Records page.
Can it be given with other vaccines? Yes. At the 4–6 year visit it's routinely given alongside the second dose of MMRV (measles, mumps, rubella, varicella), at a different injection site.
Because the timing lines up with school entry, this is one of the vaccines public health pays close attention to when reviewing records. Making sure the 4–6 year booster is given and reported helps avoid "missing immunization" letters later on.
Reporting: As with all vaccines, parents and caregivers are generally responsible for reporting their child's immunizations to their local public health unit, since healthcare providers do not always do this automatically. Make sure the booster is recorded on the immunization record (the "yellow card") and reported — for example, through Immunization Connect Ontario (ICON) if your area uses it.
Exemptions: If your child cannot receive this vaccine for medical reasons, or you are seeking a non-medical exemption, see the School Requirements hub for the process.
Two Tdap-IPV products are used in Ontario: Adacel®-Polio (Sanofi Pasteur) and Boostrix®-Polio (GSK). Either may be used. The information below reflects their Health Canada product monographs. Neither is a live vaccine. ("Tdap" uses a lower-case "d" and "p" to indicate reduced amounts of the diphtheria and pertussis components, appropriate for a booster.)
| Ingredient / Component | Category | Why it's there | Plain-English explanation |
|---|---|---|---|
| Tetanus and diphtheria toxoids; acellular pertussis components; inactivated poliovirus (types 1, 2, 3) | Active ingredients | These train the immune system to recognize each of the four diseases. | Toxoids are inactivated toxins — they can no longer cause illness but still prompt an immune response. "Acellular" pertussis uses purified pieces of the bacteria rather than the whole cell. The polio component is inactivated (killed), so it cannot cause polio. |
| Aluminum phosphate (or aluminum hydroxide) | Adjuvant | Helps the immune system respond more strongly. | An aluminum-based adjuvant used in small amounts, with a long track record of safe use in vaccines. |
| 2-phenoxyethanol | Preservative | Helps prevent contamination of the vaccine. | A preservative used in small amounts in some injectable and other products. |
| Polysorbate 80 | Stabilizer / emulsifier | Helps keep the vaccine's ingredients evenly mixed and stable. | A common ingredient in many foods, cosmetics, and medications. |
| Formaldehyde and/or glutaraldehyde (trace amounts) | Manufacturing process residual | Used during manufacturing to inactivate the toxins and virus; trace amounts may remain. | Used to safely inactivate the components during production. Any remaining amount is very small — less than the body naturally produces during normal metabolism. |
| Neomycin, polymyxin B (trace amounts) | Manufacturing process residual (antibiotics) | Used during manufacturing to help prevent bacterial contamination. | Trace amounts may remain; relevant for anyone with a known severe allergy to these specific antibiotics. |
Expected / common side effects
Timing and duration: These reactions typically begin within a day of the vaccine and usually resolve within 1–2 days.
Home care: A cool compress can help with soreness at the injection site. Acetaminophen or ibuprofen may be used as directed to reduce discomfort or fever — check with a pharmacist or healthcare provider on appropriate dosing for your child's age and weight. Children under 19 should not be given ASA (Aspirin) or products containing salicylates.
When to call a healthcare provider: If fever is high or persistent, if your child seems unusually unwell, or if you're simply unsure — it's always reasonable to call.
Mild side effects can happen as the immune system responds. Many children have no side effects at all, and that does not mean the vaccine didn't work.
Rare but important
What clinics do to reduce risk: Clinics ask about allergy history before vaccination and are equipped with epinephrine and trained staff in case of a severe allergic reaction.
Observation period: Many clinics recommend staying nearby for about 15 minutes after vaccination, as severe allergic reactions — though rare — typically occur shortly after the injection.
Get urgent help now if your child has:
If any of these occur, go to the nearest emergency department or call 911. Otherwise, contact a healthcare provider and let them know what happened — this information also helps with vaccine safety monitoring.
Speak with a healthcare provider before this vaccine if:
These usually do NOT require delaying this vaccine:
Where to get it
Typically given by a family doctor or nurse practitioner during routine well-child visits. Some public health units also offer clinics.
What to bring
Your child's immunization record (the "yellow card"), health card if available, and a list of any allergies or previous reactions.
If you're behind
Catching up does not mean restarting. Visit the Catch-Up & Missing Records page or ask your provider for a review.
If records are missing
Contact your local public health unit — they may have records on file, or can advise on next steps.
If vaccinated outside Ontario
Bring any available records to a healthcare provider for review — products and schedules elsewhere may differ slightly from Ontario's.
Contact public health
For record reporting, school requirements, or general questions, see the Resources page for your local public health unit's contact details.
This page is based on:
Please note: This is an independent website. It is not affiliated with, endorsed by, or operated by the Government of Ontario, the Ministry of Health, or any public health unit. The information here is for general education only and is not medical advice — always consult a licensed healthcare provider about your or your child's immunizations.